This invention relates to vehicles which have brakes which are normally applied by spring pressure, and are releasable by hydraulic pressure. In such vehicles failure of the power plant or related systems such as the hydraulic system, can prevent hydraulic release of the normally applied brakes, which in turn will prevent towing of the vehicle to repair facilities for servicing.
Prior art devices, such as that shown in U.S. Pat. No. 3,744,331, provide means for disconnecting the final drive train between the brake and the traction gear to allow towing. However such devices have the disadvantage of rendering the brake unavailable for use during the towing operation.